Communication among computing devices typically occurs through networks. In packet-switched networks, each network device is assigned an internet protocol (IP) address to identify the particular device in the network.
The dominant standard for IP addresses is internet protocol version four (IPv4). IPv4 addresses are 32 bits (4 bytes) in length, which limits the possible number of IPv4 addresses available for use to 4,294,967,296 (2^32). As the number of client devices seeking network connections continues to grow, the number of available IPv4 addresses continues to decline and will eventually reach zero. This problem is known as IPv4 address exhaustion.
Internet Protocol version 6 (IPv6) is an Internet Protocol version that has been developed to succeed IPv4. IPv6 has a vastly larger address space than IPv4. This results from the use of a 128-bit address. The IPv6 address space supports 2^128 addresses.